AJCS 13(05):695-700 (2019) ISSN:1835-2707 doi: 10.21475/ajcs.19.13.05.p1340

Initial growth of carnauba ( prunifera) progenies under saline water

Emanuel Lucas Bezerra Rocha, Poliana Coqueiro Dias Araujo*

Federal University of the Semi-Arid, Department of Agronomy and Forestry Sciences, Street Francisco Mota, 572, Costa and Silva, CEP 59625-900, Mossoró, RN,

*Corresponding author: [email protected]

Abstract

The carnauba ( [Miller] H. E. Moore) is a palm that has multiple uses and is of great economic and social importance for extractive families in Northeast Brazil. The objective of this work is to analyze the effect of saline water on the production of different progenies of carnauba. The experiment is arranged in a 5 x 36 factorial scheme in a randomized complete block design, with five replications and five per replication. The treatments consist of five levels of irrigation water salinity (with commercial NaCl levels, free of iodine: 0, 25, 50, 75, and 100 mM) and 36 free-pollination progenies. The following characteristics are evaluated: foliar length (H), collecting diameter (DC), survival rate (TS), number of (NF), dry shoot mass (MSPA), dry mass of the system (MSSR), and dry mass ratio of the root system to the shoot. The results reveal similar behavior among the progenies for the evaluated characteristics. However, significance is observed for the parameters length, collection diameter, and survival rate when the progenies are subjected to salinity above 9.6 dS m-1. Another significant factor is the accumulation of Na+ in the aerial and radicular parts in salinity levels of 7.1, 9.6, and 12.0 dS m-1, with the root system being the most affected site. Thus, the tested progenies exhibit similar behaviors in tolerance to irrigation water salinity. Since the carnauba can produce seedlings in water with electrical conductivity of up to 9.6 dS m-1, this is characterized as a bioindicator of saline soils and is recommended for planting in degraded areas.

Keywords: Crop management; Saline stress; Seedling production; Silviculture; Tolerance to salinity. Abbreviations: H_ Foliar length; DC_ Collecting diameter; TS_ Survival rate; NF_ Number of leaves; MSPA_ Dry shoot mass; MSSR_ Dry mass of the root system; CEa _ Electrical conductivity of the irrigation water; CE_ Electrical conductivity; MST_ Total dry mass; MSSR/MSPA_ Dry matter ratio of the root system to the aerial part.

Introduction

Copernicia prunifera, commonly known as the carnauba, is soil and surface water (Bui, 2013). In these regions, the one of the main economically valuable and drought-resistant salinization of the soil is practically irreversible, since the palm in the Brazilian semi-arid region. Its exploitation leaching of accumulated salts is reduced due to the scarcity is typically carried out by small and medium producers who of freshwater of pluvial or subterranean origin. Soil use mainly the wax from its leaves and also use its stipe, salinization may also occur from anthropogenic action, petiole, , and (Reis et al., 2011; Vieira et al., 2016). which is strongly related to high levels of salts in irrigation The carnauba has important social value for the populations water and cultural ill-treatment associated with inadequate of Northeast Brazil. It is estimated that more than 200,000 drainage and soil management (Plaut et al., 2013). rural producers are economically involved in obtaining wax Salinity can result in physiological drought in a from from carnauba leaves during the dry season, when irregular change in osmotic potential. This change reduces the water rains make agricultural plantations unfeasible as sources of potential of the substrate and induces a water deficit. income (Ferreira et al., 2013). Nutritional imbalance due to high ionic concentration leads In the Brazilian semi-arid region, the carnauba occurs in to antagonistic effects on potassium uptake, water floodable areas (Rodrigues et al., 2013), including areas of absorption, and enzymatic activity. Salinity also induces riparian forest. This species is believed to present the sodium and chlorine toxicity (Hasegawa, 2013). The Mimosa characteristics of plants that can grow in environments with caesalpiniifolia Benth and Mimosa ophthalmocentra Mart. high salt concentration (Calheiros et al., 2012), and can Ex Benth are plants native to the semi-arid region. Although therefore be used in forest production and the recovery of they are adapted to the conditions of the Northeast, the two areas with salinized soils in the Northeast. plants do not tolerate soils with a high concentration of salts In the northeastern semi-arid region, soil salinization is one and osmotic potential of 1.25 and 1.5 dS ml-1, respectively of the main causes of yield decline. Intense evaporation and (Leal et al., 2015). However, other species may incomplete leaching promote the concentration of salts in even be favored when exposed to NaCl concentrations. In

695 particular, the Parkinsonia aculeata L. can grow in soils with period. Specifically, in the treatments T4 and T5, the average an osmotic potential of 7.25 dS ml-1 without its development diameter of the collection of seedlings was estimated to be and growth being inhibited. (Bezerra et al., 2013). An 5.49 cm and 5.15 cm, respectively (Fig 1). Similar results understanding of the mechanisms of tolerance and were found in a study by Temoteo et al. (2015) while susceptibility to salinity is important for the development of observing different Conilon coffee cultivars. In this study, it new techniques of crop management that allow for was demonstrated that the diameter of the stem was agricultural production under saline stress conditions. affected by the salinity of the soil as the time of exposure to Despite the carnauba’s considerable potential, research on saline stress increased in the different cultivars and water this species is still incipient. conditions. Therefore, the objective of the present work is to analyze Relative reductions of 8.8% and 14.6% were observed when the effect of saline water on the production of half-sib comparing the DC of the plants at 120 days in the T4 and T5 progenies of carnauba seedlings. treatments, respectively (Fig 1b). The salinity effect was found to be lower in the collecting diameter (Fig 1b) than in Results and discussion the leaf length (Fig 1a), which demonstrated significant reductions (p < 0.01) from treatments T4 and T5, with losses Growth of carnauba plants under the effects of salinity of 6.45% and 11.76%, respectively. This reduction in seedling growth has also been observed in fruit species, such as in a The interaction between the progenies and the salt level was study by Sousa et al. (2011), which revealed a decrease of up not significant (p > 0.01). For the progeny factor as well, no to 70% when evaluating the initial development of two significance was observed for the analyzed variables. This cashew clones under irrigation with saline water (0, 3.0, 6.0, result indicates that these progenies present a similar 9.0, and 12.0 dS m-1). This reduction is due to the early response to different levels of salinity in irrigation water. closure of the stomata as a consequence of the change in However, the salinity of the irrigation water significantly osmotic potential, which reduces the daily photosynthetic influenced (p < 0.01) the leaf length of the different rate. This phenomenon is common in the Brazilian semi-arid progenies at 30, 60, 90, and 120 days after application of the region, which has peculiar edaphoclimatic conditions: soils treatments on Copernicia prunifera (Fig 1). Among the with high concentrations of salts, an environment with a applied treatments, T4 and T5 presented a lower average for high evaporative demand, and intense solar radiation the evaluated characteristic, presenting reductions of 6.44% (Prisco, 1980). Saline stress caused reductions of 3.46%, and 14.85%, respectively, in relation to T1 (Fig 1). 5.07%, 8.19%, and 14.30% in total dry mass (Fig 2c) in The reduction in leaf length in treatments with higher treatments T2, T3, T4, and T5, respectively, in relation to the salinity content may be associated with the stress to which control (T1). With respect to dry matter of the root system the plants were subjected (Fig 1a). Stress conditions, both and dry mass of the shoot (Fig 2d), salinity significantly water and saline, induce the increase of abscisic acid. interfered with the value of the SR/PA ratio (Fig 2d) in the T5 Consequently, cell division is inhibited, causing a decrease in treatment, with a reduction of 18.61%, compared to 8.68% leaf length and foliar abscission. This reduces transpiration, in the T2 treatment. The increase in electrical conductivity of which helps lower the absorption of saline water. irrigation water is another indication that the root system of A significant influence of salinity on the survival rate (TS) was the seedlings is most affected by salinity. Furthermore, the observed (Fig 1c) on the evaluated days, which included the leaves are sensitive to high concentrations of salts. This can period from 30 to 120 days. The most negative effects were be interpreted as adaptation of the plant to saline stress. seen in the T4 and T5 treatments, corresponding to electrical Specifically, the reduction of the leaf transpiration surface is conductivity of 9.6 and 12.0 dS ml-1, respectively. This a way to save water when the osmotic potential of the soil influence may be associated with high osmotic pressure and solution becomes more negative. This change in osmotic the toxic action of elements such as Na+, Br, and Cl (Table 1), potential occurs as K reduces because Na+ increases in the which reduces the availability of water to the plants, causing leaves and roots (Table 1) due to difficulty in water physiological disturbances and possible plant-tissue death absorption (Lima et al., 2015).The reduction of the root (Gupta and Huang, 2014).The number of leaves (NF) was not system in carnauba seedlings at high levels of salinity may be significantly affected (p < 0.01) between 30 and 120 days associated with the physiological mechanism of the after application of the treatments; therefore, the negative carnauba. This mechanism stimulates growth of the aerial effects of salinity did not influence the addition of leaves part, depending on the type of palm seed, using nutritive when the plants were irrigated with salt water (Fig 1d). In a reserves in the form of protein bodies and lipids stored in general analysis of the variables presented in Figure 1, it was the endosperm (Rodrigues et al., 2013). In addition, the root inferred that the salinity level significantly affected the T4 of the carnauba reaches a depth of 15.5 cm after 60 days of and T5 treatments. These differences may be related to the sowing, potentializing the absorption zone and leading to an genetic characteristics of the genotypes used in the increase in leaf area along with a reduction in the effects of experiment. After 120 days of evaluation, there was a physiological drought. The juvenile leaves of carnauba downward trend for the characteristics evaluated at seedlings, which present stomatal indices of 5.18 ± 0.58 and different levels of salinity (Fig 1). The treatments with higher 5.17 ± 0.65 for the abaxial and adaxial surfaces, respectively, salinity content, T4 and T5, presented lower means than the are another factor to be considered. They result in less water others (Fig 1). In general, at 120 days after application of the loss from perspiration. Even in the treatment with low treatments, the collecting diameter (DC) of the Copernicia electrical conductivity (T1), the MSPA was two times higher prunifera seedlings indicated that the variation in electrical than that of the root system. Thus, even at high levels of conductivity of the irrigation water (CEa) caused a linear salinity, the carnauba presents a good percentage of survival reduction in the size of the seedlings along the evaluation

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Table 1. Chemical analyses of plant tissue of 36 half-sib progenies of carnauba (Copernicia prunifera) seedlings: PA (aerial) and PR (root) at different salinity levels (T1 = 2.0 dS m-1, T2 = 4.6 dS m-1, T3 = 7.1 dS m-1, T4 = 9.6 dS m-1, T5 = 12.0 dS m-1) 120 days after application of the treatments (TRAT). TRAT LOCAL N P K CA MG FE MN ZN CU NA T1 PA 19.3 a 0.85 a 27.1 a 5.7 a 2.2 a 969 a 106 a 36 a 6.5 a 5040 a T2 PA 24.5 a 1.27 a 26.1 a 6.8 a 2.6 a 518 b 103 a 13 b 7.0 a 6552 a T3 PA 19.3 a 0.63 a 20.5 b 4.7 a 1.8 b 593 b 48 c 38 a 3.5 a 9071 b T4 PA 18.4 a 0.95 a 20.9 b 5.1 a 1.7 b 382 c 71b 6 c 6.0 a 15119 c T5 PA 18.4 a 0.72 a 23.7 ab 4.3 a 1.5 b 210 d 81 b 1 c 5.0 a 13809 c T1 PR 28 a 2.21 a 22.9 a 10.8 a 4.5 a 2954 b 230 a 80 a 21.5 a 4536 a T2 PR 26.7 a 2.26 a 10.7 b 8.0 a 4.8 a 3467 a 180 b 65 ab 15.5 ab 6652 a T3 PR 14.9 b 1.66 a 8 b 10.1 a 4.3 a 2927 b 218 a 53 b 11 b 12801 b T4 PR 21.9 a 1.55 a 5.6 b 13.0 b 4.3 a 1432 c 165 b 39 c 6 c 17941 c T5 PR 25.4 a 1.9 a 6.4 b 14.8 b 2.5 b 147 d 73 c 39 c 8.5 bc 16228 c Means followed by the same lowercase letter in a column do not differ significantly at 5% of probability by Tukey’s test.

a) b) 20 8

15 6

10 4 ŷ = -0.2391x* + 19.362

H (cm) H R² = 0.8368 ŷ = -0.0889x* + 6.3075 5 DC (mm) 2 R² = 0.9335

0 0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 CEa ( dS m-1) CEa ( dS m-1)

c) d) 100 4 80

3

60 2 40 ŷ = -1.0186x* + 84.305 NF ŷ = -2.914x* + 337.77

TS (g) R² = 0.8954 20 1 R² = 0.9171

0 0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 CEa ( dS m -1) CEa ( dS m-1)

Fig 1. Leaf length (CF-a), collection diameter (DC-b), survival rate (TS-c), and leaf number (NF-d) of 36 half-sib progenies of Copernicia prunifera, as a function of salinity of irrigation water (CEa); (T1 = 2.0 dS m-1, T2 = 4.6 dS m-1, T3 = 7.1 dS m-1, T4 = 9.6 dS m-1, and T5 = 12.0 dS m-1).

(Fig 1c), which may reflect the adaptive characteristics of the closing movements of stomata, tropisms, solute transport in species. phloem, and energy conservation in membranes (Deinlein et al., 2014; Benito et al., 2014). In addition, the Na+/K+ cell Nutrient composition of carnauba plants under the effects homeostasis is crucial for the plant’s survival in saline of salinization conditions (Gupta and Huang, 2014; Shabala and Pottosin, 2014). In the root portion, there was a significant increase in Another significant factor (p < 0.05) was the accumulation of Ca content above the salinity level of 7.1 dS m-1 (Table 1). Na+ in the aerial and radicular parts when salinity levels were The levels of Na+ drove significant increases in Ca content 7.1, 9.6, and 12.0 dS m-1 (Table 1). The most affected was only in the root portion. the root system. An inversely proportional relationship Of the elements studied, Mg was one of the macronutrients between Na+ and K+ has been observed that is, as Na+ most affected by the Na+ increase. Significant salinity effects increases in the plant tissue, K+ tends to decrease, because were seen on the content of Mg in the aerial and root parts Na+ in the tissue competes for the same absorption site as (Table 1). The content of this element was higher in the K+, decreasing the absorption of the latter. K+ is related to aerial than in the root part, especially in salinity levels above the maintenance of cellular turgor, stretching, opening and 4.6 dS m-1. The increase in salinity in the plant is closely 697

a) b) 6.2 3 6.1

2.5

6 5.9 2 5.8 1.5 5.7 ŷ = -0.0501x* + 6.1936 ŷ = -0.0652x* + 2.7525 MSPA (g)MSPA 1 5.6 R² = 0.8034 (g) MSSR R² = 0.9841 5.5 0.5 5.4 0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 CEa ( dS m-1) CEa ( dS m-1) c) d) 8.8 50 8.6 40

8.4 8.2 30 8 7.8 20 MST(g) ŷ= -0.1153x* + 8.9461 ŷ = -0.7855x* + 44.713 7.6 R² = 0.9467 10 R² = 0.9501

7.4 (%) MSSR/MSPA 7.2 0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 CEa ( dS m-1) CEa ( dS m-1) Fig 2. Dry mass of the aerial part (MSPA-a), root system (MSSR-b), total dry mass (MST-c), and dry matter ratio of the root system to the aerial part (MSSR/MSPA-d) of 36 half-sib progenies of Copernicia prunifera, as a function of salinity in irrigation water (CEa), at 120 days after application of the treatments (T1 = 2.0 dS m-1, T2 = 4.6 dS m-1, T3 = 7.1 dS m-1; T4 = 9.6 dS m-1, and T5 = 12.0 dS m- 1). related to the Na+/K+ ratio (Silva et al., 2014). Thus, this have an effect after 120 days of sowing. Thus, it is evident relationship is the clearest indicator of sodium toxicity. It that phenology influences the salinity tolerance of the promotes an increase in the absorption of the sodium ion to carnauba. the detriment of potassium absorption, ultimately inhibiting The tolerance of the carnauba to salinity of irrigation water the activity of the enzymes that require potassium. This during the production of seedlings may also be associated leads to an ionic imbalance in the plant (Benito et al., 2014). with genetic differences within the species. According to Moreover, salinity impairs plant development by altering its Gupta and Huang (2014), genetic variations exist in nutrient balance, cellular metabolism, and physiological and tolerance to salt in irrigation water and in the soil, and the chemical processes (Hasanuzzaman et al., 2014; Zia et al., degree of tolerance varies among species and plant varieties 2011). These changes result in morphological adaptations so within a species. This finding was confirmed by Fernandes et that the carnauba can tolerate the stress. Thus, during the al. (2011) when they studied the sensitivity of different course of the experiment, the extent to which the exposure varieties and hybrids of lemon trees tolerant to saline of the seedlings to saline stress exceeded the tolerance of conditions. the plant was observed. They developed modifications such as burns and necroses, falling of thorns, and chlorosis along Materials and methods and tortuosities in the leaves. These modifications reduced the growth and sometimes caused the death of the young Plant materials plant (Jindal et al., 1976; Maeda et al., 2010; Oliveira et al., 2012). This explains the significant reduction in growth of The experiment was conducted at the seedling production seedlings in treatments with salinity above 9.6 dS m-1 of nursery of Federal University of the Semi-Arid, Mossoró, electrical conductivity (Fig 1).In general, this study reveals Brasil. For producing the seedlings and establishing the that the carnauba tolerates a salinity level of 9.6 dS m-1. The experiment, 36 matrices were selected based on the natural tolerance limit is an excellent primary bioindicator of soils survival capacity of the carnauba in saline soils. Thus, 9 with high saline concentrations that change according to matrices were selected in four populations established in variations in the environment. This value is higher than that salinized areas, and the experiments were conducted with found by Holanda et al. (2011), who studied the same the free-pollination progenies of these matrices. The seeds species subjected to saline stress and demonstrated that the used were obtained from with yellow-green coloration development of the carnauba was compromised in collected during the maturation stage. These fruits were concentrations greater than or equal to 3 dS m-1. These packed in plastic bags and transported to the post-harvest authors studied the carnauba for up to 120 days after laboratory, where they were stored. sowing. However, in the present study, salinity started to

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Conduction of study Acknowledgements The seeds were subjected to the pre-soaking process in plastic bottles, where they remained for the time necessary The authors thank the National Council for Scientific and for protrusion of the cotyledonary petiole. After this, 15 Technological Development (Conselho Nacional de seeds were selected from each lot for sowing, standardized Desenvolvimento Científico e Tecnológico - CNPq). by cotyledonary petiole length (4 mm). The pre-germinated seeds were sown horizontally at a depth of 2 cm, three References seeds per bag of polyethylene with a capacity of 1 L, filled with organic substrate and exposed daily to irrigation with Benito B, Haro R, Amtamann TAC, Dreyer I (2014) The twins natural tap water. K+ and Na+ in plants. J Plant Physiol. 171:723–731. Following germination, the plants were watered daily with Benicasa MMP (1988) Análise de crescimento em plantas tap water for 180 days. After this period, irrigation (noções básicas). 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